ANILINE GREENS.

203

Nicholson’s Blue (4 B.)

hours it still amounts to 4 atmospheres. A tube is then fixed to the screw-tap, which leads to a worm, communicating with a series of large globes, andthe distillation is begun.

When the distillation is at an end the boiler is opened, and the semi-fluidcontents are drawn out, and put to dissolve in a boiler containing 600 litres ofdistilled water and fitted with a steam-jacket. The green dissolves entirely,whilst the violet matters remain insoluble, with the exception of a smallquantity which is kept in solution by the acid set free during the reaction.This residue is removed by a first filtration. To the filtrate about 35 kilos, ofcommon salt are added; the boiling is continued, and the free acid isneutralised by crystalline carbonate of soda. To regulate the quantity, a

Saffranine Pink.